The present invention relates generally to presses, pressing methods, and cutting tool green bodies made from pressing and, more particularly to presses for making cutting tool green bodies having helical flutes, and pressing methods for making cutting tool green bodies having helical flutes.
It is relatively common in the iron powder industry to manufacture helical gears via a pressing operation. U.S. Pat. No. 5,366,363, U.S. Pat. No. 6,004,120, U.S. Pat. No. 6,440,357, U.S. Pat. No. 6,156,265, and U.S. Pat. No. 3,694,127 are examples of presses for manufacturing helical gears. On the other hand, cemented carbide tools for holemaking or milling of the type that has a helical flute, which are typically of much smaller diameter than helical gears, are typically produced either by metal injection molding or non-near net shape production methods like machining or grinding. US 20060288820 A1 discloses a cutting tool green body made by extrusion.
The inventor has discovered that helical pressing can facilitate production of cemented carbide cutting tool green bodies for holemaking or milling of the type that have a helical flute by pressing of certain helical insert geometries. Such a pressing operation can improve production economy for such products when compared to other production methods like injection molding and extrusion.
A problem with helical pressing is that, of the tool members making up the press tool in the press, at least two must be able to rotate to be able to press helical blanks. Many current helical press manufacturers utilize a plurality of hydraulic cylinders and mechanical components to advance, withdraw, and rotate punches relative to a die, resulting in a substantial amount of relatively bulky mechanical and hydraulic equipment.
It is desirable to provide a more compact drive system and to provide a helical press suitable for manufacture of cutting tool green bodies having helical flutes. The inventor has recognized that multi-axial presses, pressing with several punches independently and having electrical drives rather than hydraulic cylinders, may be suitable for helical pressing of cutting tool green bodies, particularly where pressing forces are in a lower range than is typical of the forces used in manufacturing helical gears. These electrical drives, often based on electrical motors, lead screws like ball screws or roller screws, can provide positioning accuracy that is superior to hydraulic cylinders and often better than ±2 μm. This drive system then utilizes the available positioning accuracy in the electrical multi-axial press' electrical drives rather than having to secure for that within its own design.
According to an aspect of the present invention, a press is provided for making a cutting tool green body having at least one helical flute, wherein the press comprises a die having an opening with at least one helical protrusion, a top punch having at least one helical groove having a shape that matches a shape of the helical protrusion, a bottom punch having at least one helical groove having a shape that matches the shape of the helical protrusion, and a first electrical punch drive system arranged to simultaneously rotate, relative to a longitudinal axis of the opening in the die, and axially advance, into a top end and along a direction of the longitudinal axis of the opening in the die, the top punch, the press being further arranged with a second electrical punch drive system arranged to simultaneously rotate, relative to the longitudinal axis of the opening in the die, and axially advance, into a bottom end and along the direction of the longitudinal axis of the opening in the die, the bottom punch.
According to another aspect of the present invention, a method of making a cutting tool green body having at least one helical flute is provided and comprises supplying an opening in a die having at least one helical protrusion for forming the helical flute with a metal carbide powder, and compressing the powder by operating a first electrical punch drive system to simultaneously rotate, relative to a longitudinal axis of the opening in the die, and axially advance, into a top end of the opening and along a direction of the longitudinal axis of the opening in the die, a top punch having at least one helical groove having a shape that matches a shape of the helical protrusion, and operating a second electrical punch drive system to simultaneously rotate, relative to a longitudinal axis of the opening in the die, and axially advance, into a bottom end of opening and along a direction of the longitudinal axis of the opening in the die, a bottom punch having a helical groove having a shape that matches a shape of the helical protrusion.